1. Field of the Invention
The present invention relates to a back irradiating type solid state imaging device having an advantage of a CCD image sensor and that of a CMOS image sensor.
2. Description of the Related Art
There are two types of semiconductor apparatuses which have been widely utilized as an image sensor (an imaging device). One of them is a CCD image sensor and the other is a CMOS image sensor.
For example, a CCD image sensor described in Japanese Patent No. 2821062 has an advantage that an SN ratio is high and an optical characteristic is excellent, and an imaging synchronism of a plurality of pixels provided on a light receiving surface is implemented, and a disadvantage that plural types of source voltages such as a charge reading voltage for reading a signal charge from a pixel to a charge transfer path and a transfer voltage for driving the charge transfer path are required and a consumed power is increased.
On the other hand, for example, a CMOS image sensor described in JP-A-2006-32497 has an advantage that a consumed power is low and an operation is carried out with a single power supply of 3.3 V, and random access and parallel reading can be performed, and a disadvantage that an SN ratio is low and an imaging synchronism is not present.
Thus, the CCD image sensor and the CMOS image sensor have the respective advantages and disadvantages. Therefore, the CCD image sensor is mainly employed for an imaging apparatus for a video and a digital camera requiring a high image quality and a high sensitivity, for example, and the CMOS image sensor is often employed in an imaging module for a portable telephone.
In consideration of the respective advantages and disadvantages, it is selected whether an image sensor to be loaded onto a photographing apparatus is set to have a CCD type or a CMOS type. However, a developer of the photographing apparatus has a great demand for an image having both of the advantages.
For example, there has been highly demanded an image sensor which adds and reads a plurality of pixel signals and executes a high speed photographing operation having a high sensitivity in a low consumed power to implement an increase in speeds of AE and AF in an animation photographing operation and image pickup having a high image quality can be implemented with a high SN ratio in a static image photographing operation.